Sets — O/L Mathematics

What must I remember about Sets?

• A set is a well-defined collection of distinct objects; universal set (ε or ξ) contains all elements under consideration.
• Intersection (A ∩ B): The set of elements belonging to both A and B.
• Union (A ∪ B): The set of elements belonging to A, or B, or both.
• Complement of set A (A'): The set of all elements in the universal set that do not belong to A.
• Fundamental cardinality relation for two finite sets: n(A ∪ B) = n(A) + n(B) - n(A ∩ B); n(ε) = n(A ∪ B) + n((A ∪ B)').

Test yourself (1 minute)

1. The double-counting trap

   In word problems, 'students who like tea' includes those who like BOTH tea and coffee; students who like ONLY tea = n(A) - n(A ∩ B).

2. Venn diagram region labelling

   Fill the intersection region n(A ∩ B) first before populating the 'only' crescent regions.

3. Outside the circles region

   Never forget elements belonging to neither set: n((A ∪ B)') = n(ε) - n(A ∪ B).

Practise Sets questions today

Source: NIE G.C.E. (O/L) Mathematics Syllabus (Grade 10, Unit 17)

What should I study first?

What comes next?

Next in the syllabus

Where does Sets fit in the syllabus?

Grade 10 · Term 2 · Grade 11 · Term 3